for non-surgical Class III malocclusion

Transcription

1 for non-surgical Class III malocclusion Lívia Monteiro BICHARA, Mônica Lídia Castro de ARAGÓN, Gustavo Antônio Martins BRANDÃO, David NORMANDO Universidade Federal do Pará, Faculdade de Odontologia, Belém, PA, Brasil. Corresponding address: David Normando - Rua Boaventura da Silva, Belém - PA Brazil - Phone: davidnormando@hotmail.com ABSTRACT T could interfere with orthodontic treatment time. Objective: To identify variables and their effect size on orthodontic treatment time of Class III malocclusion. Material and Clinical charts, cephalometric radiographs, and pre and posttreatment dental casts were evaluated. Age, sex, PAR index at T1 and T2, overjet, missing teeth, extractions, number of treatment phases, missed appointments, appliance breakages, and cephalometric variables SNA, SNB, ANB, Wits, SnGoGn, CoA, CoGn, IMPA, 1.PP were investigated by multiple linear regression analysis and stepwise method at p<0.05. The sample was also divided into two groups: Group 0-2 (patients who had missed two clinical appointments or less) and Group >2 (patients who missed more than 2 appointments), to detect the Average treatment time was months. Multiple regression analysis showed that missed appointment (R2=0.4345) and appliance breakages (R2=0.0596) are the only variables on PAR T2 was observed for those patients. Conclusion: Orthodontic treatment duration in No occlusal, cephalometric, or demographic variable obtained before treatment was able Keywords: INTRODUCTION Orthodontic treatment duration has always been a major concern to both patients and professionals. In an attempt to predict treatment costs, patients want to know how long their orthodontic treatment will take 6. Likewise, braces can cause discomfort and inconveniences related to daily routine changes. For orthodontists, a more precise prediction of the duration of a treatment can earn patients trust, representing a valuable tool for a successful treatment 26. Truth and accurate time estimation are two of the most frequent recommendations, followed by reduction in treatment fees 19. Also, orthodontic treatment has biological costs and long treatments have been associated with root resorption 17,22. Therefore, a better understanding J Appl Oral Sci. 431 of the factors influencing treatment time can orthodontists to manage treatment, achieving, thus, great results in less time. Factors that could interfere on treatment duration include sex 11, pretreatment ANB value 11,27, overbite 27, crowding 2,27, extractions 2,11,27, time between appointments 2, treatment phases 29, age 10,20, overjet 6,20,technique 26, patient compliance (including missed appointments and debonds) 16,20,27, public or private practice 30, oral hygiene 12,27, scholar grades 12, caries 12, restorations 12, arch coordination 12, parent s occupation 12. However, to the best of our knowledge, all previous studies, including a systematic review 15, focus on treatment duration of Class I and II malocclusion subjects. Only association between

2 Class III molar relationship and treatment time has been described 31. This might be due to the low prevalence of Class III malocclusion, around 5% of a population, 7,18 and the high acceptance of treatment need by professionals and patients for those cases 7,9,21. Class III malocclusion has particular characteristics that differ from others malocclusions. Despite its low prevalence 9,21, the impact on lifequality is high 7. Also, Class III growth pattern has some particularities when compared with Class I and Class II patients, as more vertical pattern and longer growth peak for Class III than for Class I patients 4. While mandibular growth works for the Furthermore, relapse after orthodontic treatment is frequently reported 8. The knowledge of which variables can interfere in Class III treatment duration might help clinicians to act upon controllable variables, performing objective is to evaluate variables present in the orthodontic intervention for Class III malocclusion MATERIAL AND METHODS This study received ethical approval from The Research Ethics Committee of the Federal University of Pará (number , 2014). Sample size was estimated using GPower 3.1 software. To detect a 0.35 effect size using six independent variables, alfa level of 0.05, and power of 0.8, we needed 19 female and 26male) consecutively treated Class III patients were retrospectively selected from of an experienced orthodontist. The inclusion criteria were: non-syndromic dental Class III subjects with Class III molar relationship; edge to edge incisor relationship or anterior crossbite; permanent dentition treated with full orthodontic appliance in both arches. Exclusion criteria comprised patients who had more than one missing tooth per hemiarch, who missed over 16 appointments, and those who were surgically treated. No patient had TAD s placed before or during treatment or were treated with self-ligating brackets. Data were collected from clinical records, dental casts, and cephalometric radiographs. The ages at the beginning of treatment (T 1 ) ranged from 9.5 to 48 years old, and mean age was years. Treatment was performed using preadjusted twin brackets with.022x.028 slot. The information collected from dental records were age, sex, duration of orthodontic treatment, number of treatment phases, number of teeth extractions due to treatment plan, number of missing teeth before treatment, missed appointments, and appliance breakages (Figure 1). Sagittal incisor relationship was evaluated based on the overjet section of PAR index. Each interval longer than 45 days between two consecutive clinical visits were considered as missed appointment. The number of extractions or missing teeth was sought in the radiographs from before and after treatment. Dentoskeletal measurements SNA, SNB, ANB, Wits, SnGoGn, CoA, CoGn, IMPA, and 1.PP were obtained variables. Dental casts were assessed to obtain PAR index before (T 1 ) and after orthodontic treatment (T 2 ), Dependent variable Variable type Independent variables Treatment duration Patient demographics Sex Age at the beginning of treatment Occlusion characteristics Overjet* Number of missing teeth T1 PAR T2 PAR Occlusion improvement T1PAR T2PAR Cephalometric features SNA, SNB, ANB, Wits, SnGoGn, CoA, CoGn, IMPA, 1. PP Treatment characteristics Number of teeth extracted Number of treatment phases Patient compliance Number of missed appointments Number of brackets and bands breakages *Measured by PAR index Figure 1- Variables analyzed in the study J Appl Oral Sci. 432

3 BICHARA LM, ARAGÓN MLC, BRANDÃO GAM, NORMANDO D according to Richmond, et al. 23 (1992), using a digital caliper (Mitutoyo- Suzano, São Paulo, Brazil). PAR index 23 was doubled measured in twenty dental casts with a 30-day interval. All data retrieved from dental casts and cephalometric radiographs correlation test was calculated to evaluate the reliability of measurements. Correlation between treatment duration (dependent variable) and continuous variables retrieved from patients records was analyzed using Pearson s Correlation test. The Student s t test for 2 independent samples was applied to search for differences in treatment duration between genders. Then, multiple linear regression was used to orthodontic treatment time (dependent variable). The sample was divided in 2 groups regarding the number of missed appointments to verify if it was related to treatment duration and PAR at T 2. Patients with 0 to 2 missed appointments were gathered in Group 0-2 (n=27; 18 male, 9 female), and patients with more than 2 missed appointments in Group >2 (n=18; 9 male and 9 female). Normal test and descriptive statistics were calculated. Student t test was applied to evaluate differences between group variables with normal distribution, and, for variables with abnormal distribution, Mann- Whitney test was applied. Statistical analysis was performed with Bioestat 5.3 software (Mamirauá Institute, Belém, Pará, at 5%. RESULTS An excellent reliability of PAR index measurements was observed (ICC=0.9541, p<0.001). Mean treatment time for Class III subjects was of months (ranging from to 54.96). Patient compliance, featured as the number Table 1- for each variable assessed in the study Variables Mean/ Median SD Min Max r p-value Treatment duration Age at the beginning of treatment Overjet (PAR index for incisors) Number of broken brackets or bands * Missed appointments <0.0001* Missing teeth Extracted teeth PAR T * PAR T * Occlusion improvement (PAR T1 - PAR T2) SNA SNB * ANB Wits SnGoGn * CoA CoGn IMPA PP Frequency Number of treatment phases 1 Phase 64% 2 Phase 36% J Appl Oral Sci. 433

4 Table 2- class III treatment duration (F=9.99, <0.0001) Variables R2 P Missed appointments Debonded brackets or bands PAR T PAR T SNB SnGoGn of appliance breakages (r=0.4195, p=0.004) and missed appointments (r=0.6595, p<0.0001), treatment characteristics PAR at T 1 (r=0.3251, p=0.029), PAR at T 2 (r=0.349, p= ), and skeletal features SNB (r= , p=0.02), SnGoGn (r=0.3532, p=0.017) were found to have duration (Table 1). These variables were included in the multiple regression model. Patient s demographics, number of orthodontic treatment phases, overjet, number of missing teeth, number of teeth extracted, treatment improvement (PAR T 1 -T 2 ), and the other cephalometric measurements SNA, ANB, Wits, CoA, CoGn, IMPA and 1.PP had no association with treatment duration. Also, no difference was found between male and female concerning treatment time (p=0.41). Therefore, these variables were not included in the multiple regression model. Results after multiple regression linear test and stepwise regression showed that around half of treatment duration (R 2 =0.4944) could be predicted by two variables: missed appointments (R 2 =0.4345, p=0.0002), followed by the number of debonded brackets and bands (R 2 =0.0596, p=0.0241). The cephalometric measurements SnGoGn (R 2 =0.0322) and SNB angle (R 2 = ), and malocclusion index PAR att 1 ( R 2 =0.0275) and PAR at T 2 (R 2 =0.0204) appointment was found to add about 1.5 months to the treatment duration. (p=0.02) between Group 0-2 (mean= 27.01±7.56 months) and Group >2 (mean= 36.15±11.29 months) for treatment duration. The PAR index at T 2 (p=0.098) when patients with fewer missed clinical visits were compared with those who had more missed appointments. DISCUSSION How long will my treatment last? is one of the most common questions asked by patients seeking for orthodontic treatment. To answer it, the orthodontist should focus on which variables could interfere with the treatment progress. Although several studies have investigated factors associated with treatment duration for Class I or Class II malocclusion patients, to the best of our knowledge, just one study 31 gives some information about duration of Class III malocclusion treatment. of molar Class III position on treatment duration treatment duration was found. These data would be also indispensable for future investigations on treatment types and effectiveness of results. Previous reports evaluating adult patients 16 showed that the amount of missed appointments is the factor that affects treatment duration (43.75%) of Class I and Class II patients the most. These This is a valuable information for orthodontists, since the patient also assumes some of the responsibility for the treatment time and it can persuade the patient into having good compliance. Appliance breakages were weak, but statistically associated with treatment time in this study (R 2 =0.0596), as previously described 6,16,20. Increments in treatment duration might be due to the necessity of returning to a lighter arch wire or the impossibility of treatment evolution in that month. appears to have a greater effect on duration of orthodontic treatment in Class III patients. This might occur since it is known that moderate to severe Class III malocclusions can have a considerable impact on patient s aesthetics and quality of life, keeping them more motivated and easy to handle. Clinically, this motivation should be increasingly utilized toward a shorter treatment duration. J Appl Oral Sci. 434

5 BICHARA LM, ARAGÓN MLC, BRANDÃO GAM, NORMANDO D A previous study 1 reported that missed appointments and appliance repairs explained 30.6% of treatment duration. A different study 20 also shows that total brackets or bands breakage affects orthodontic treatment duration in teenage patients; authors regarding missed appointments. Maybe this could be explained by the fact that adolescents are more likely to accept parent control; therefore more assiduous than older adolescents or young adults. Furthermore, intermaxillary elastics 24 are quite often required in Class III compensatory treatment, demanding good patient compliance. Peer Assessment Rating (PAR) was used to quantify the severity of the malocclusion given that it is a valid and reliable method: the higher the index, the greater the amount of malocclusion of the patient. PAR index at T 1 and T 2 showed no time. A possible explanation for this is the high PAR T 1, requirement of continuously using elastics is not met, the establishment of good occlusal relationship No statistical difference was found among patients who missed zero to two appointments and patients who missed more than two appointments fact that a longer treatment time was necessary in Group >2 to obtain an orthodontic outcome similar to that of group 0-2 indicates that obtaining good longer treatment time. study at the beginning of Class III treatment, differing from previous investigations examining Class I and Class II malocclusion 6,20,30. Therefore, other pretreatment or external factors, not included in this study, might be the reason why patients are skipping appointments. the literature shows no difference among patients treated for Class II malocclusion in one and two phases 9 unnecessary. Most Class III patients who seek for treatment in a younger age have more severe malocclusion 14,25 an orthopedic expansion and maxillary protraction. Consequently, most of the time, second phase appliance. III malocclusion, some reports on Class II patients describe an association between overjet and treatment duration 12,20. Initial positioning of upper and lower anterior teeth and mandibular growth are not favorable to non-surgical Class III treatment 13,28. Frequently, the upper incisors show compensatory protrusion while the lowers have lingual inclinations, limiting the amount of negative overjet that can be treated without surgery. Nevertheless, Class II division 1 patients have proclined upper incisors 25, which is favorable for compensatory treatment. Another factor regarding Class III treatment is that severe anterior crossbite is often related with substantial and evident skeletal discrepancies, requiring surgical treatment 3, unlike Class II patients, which skeletal discrepancies are more aesthetically acceptable 1,5 and can be treated in a compensatory manner. Treatment involving extractions and missing. Space closure can be a time-consuming treatment phase 23 ; however, they are correctly indicated. This study had some methodological limitations, such as using a retrospectively selected unicenter sample. However, it is a consecutively treated sample, which decreases the risk of bias. Another limitation of our study is the non-inclusion of surgical patients in the sample, leaving out a large number of Class III cases available in the been important to verify the impact of conducting surgical treatment on treatment duration in Class III patients. Failure to meet the estimated treatment time frequently damages the doctor-patient relationship by decreasing the patient s trust. Biologically, elongated treatment time have been related to increased probability of root resorption 17,22. Therefore, the awareness of the factors contributing to treatment overtime can help orthodontists to control some of these variables and perform a having smoother relationship with patients and that duration of orthodontic treatment in Class III patient compliance. Thus, it seems crucial to inform patients about their role in the treatment progress patient s cooperation. CONCLUSION No variable obtained before treatment was able to give some prediction about treatment time in this sample of Class III patients. Patient cooperation was associated with approximately 50% of the variation in treatment time for Class III patients. Therefore, it seems necessary to seek for strategies that may encourage patient cooperation during orthodontic treatment. J Appl Oral Sci. 435

6 Other variables, such as surgery need, not included in this study, should be investigated. REFERENCES attractiveness of different antero-posterior and vertical proportions. Eur J Orthod. 2011;33: Alger DW. Appointment versus treatment time. Am J Orthod Dentofacial Orthop. 1988;94: Auconi P, Scazzocchio M, Cozza P, McNamara JA Jr, Franchi L. Prediction of Class III treatment outcomes through orthodontic data mining. Eur J Orthod. 2015;37: Baccetti T, Franchi L, McNamara JA Jr. Growth in the untreated Class III subject. Semin Orthod. 2007:13: Barroso MC, Silva NC, Quintão CC, Normando D. The ability of orthodontist and laypeople to discriminate stepwise advancements in Class II retrognathic mandible. Prog Orthod. 2012;13: Beckwith FR, Ackerman RJ Jr, Cobb CM, Tira DE. An evaluation of factors affecting duration of orthodontic treatment. Am J Orthod Dentofacial Orthop. 1999;115: on quality of life attributed to malocclusion by adolescents with normal occlusion and Class I, II and III malocclusion. Angle Orthod. 2008;78: Bondemark L, Holm AK, Hansen K, Axelsson S, Mohlin B, Brattstrom V, et al. Long-term stability of orthodontic treatment and patient satisfaction. A systematic review. Angle Orthod. 2007;77: Dimberg L, Lennartsson B, Söderfeldt B, Bondemark L. Malocclusions in children at 3 and 7 years of age: a longitudinal study. Eur J Orthod. 2013;35: Dyer GS, Harris EF, Vaden JL. Age effects on orthodontic treatment: adolescents contrasted with adults. Am J Orthod Dentofacial Orthop. 1991;100: Fink DF, Smith RJ. The duration of orthodontic treatment. Am J Orthod Dentofacial Orthop. 1992;102: Fisher MA, Wenger RM, Hans MG. Pretreatment characteristics associated with orthodontic treatment duration. Am J Orthod Dentofacial Orthop. 2010;137: Janson G, Souza JE, Alves FA, Andrade P Jr, Nakamura A, Freitas MR, et al. Extreme dentoalveolar compensation in the treatment of Class III malocclusion. Am J Orthod Dentofacial Orthop. 2005;128: Jeremiah HG, Cousley RR, Newton T, Abela S. Treatment time ad oclusal outcome of orthognathic therapy in the east of England region. J Orthod. 2012;39: Mavreas D, Athanasiou AE. Factors affecting the duration of orthodontic treatment: a systematic review. Eur J Orthod. 2008;30: Melo AC, Carneiro LO, Pontes LF, Cecim RL, Mattos JN, Normando D. Factors related to orthodontic treatment time in adult patients. Dental Press J Orthod. 2013;18: Nanekrungsan K, Patanaporn V, Janhom A, Korwanich N. External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation. Imaging Sci Dent. 2012;42: socioeconomic status on the prevalence of malocclusion in the primary dentition. Dental Press J Orthod. 2015;20: O Connor PJ. Patients perceptions before, during and after orthodontic treatment. J Clin Orthod. 2000;34: Popowich K, Nebbe B, Heo G, Glover KE, Major PW. Predictors for Class II treatment duration. Am J Orthod Dentofacial Orthop. 2005;127: and orthodontic treatment need in the United States: estimates from the NHANES III survey. Int J Adult Orthod Orthognath Surg. 1998;13: Rakhshan V, Nateghian N, Ordoubazari M. Risk factors associated with external apical root resorption of the maxillary incisors: a 15-year retrospective study. Aust Orthod J. 2012;28: Richmond S, Shaw WC, O Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992;14: Sayin MO,Türkkahraman H. Cephalometric evaluation of non-growing females with skeletal and dental Class II, division 1 malocclusion. Angle Orthod. 2005;75: Shelton CE Jr, Cisneros GJ, Nelson SE, Watkins P. Decreased treatment time due to changes in technique and practice philosophy. Am J Orthod Dentofacial Orthop. 1994;106: Shia GJ. Treatment overruns. J Clin Ortod. 1986;20: Skidmore KJ, Brook KJ, Thomson WM, Harding WJ. Factors Dentofacial Orthop. 2006;129: Troy BA, Shanker S, Fields HW, Vig K, Johnston W. Comparison of incisor inclination in patients with Class III malocclusion treated Dentofacial Orthop. 2009;135:146.e1-9. randomized clinical trial of early Class II treatment. Am J Orthod Dentofacial Orthop. 2004;125: Turbill EA, Richmond S, Wright JL. The time factor in national health service practices? Community Dent Oral Epidemiol. 2001;29: complexity index for assessing the relationship of treatment duration and outcomes in a graduate orthodontics clinic. Am J Orthod Dentofacial Orthop. 2008;133:9.e1-13. J Appl Oral Sci. 436